In known machines of this type, the drive of all rollers is taken from one single general drive for the printing mechanism, namely from the drive of the printing rollers. This drive must be converted many ways for the individual rollers. For example, the distributing roller must not only be driven rotatingly with a certain peripheral speed, but it must also be axially movable back and forth, in order to achieve an application of color which is as even as possible over the entire width and periphery therof. The axial movement of the distributing roller relative to the roller which cooperates with it is achieved in conventional machines by a cross thread on the drive spindle, wherein the reversal of the direction of movement occurs automatically at the end of the respective stroke through a fork. One must thereby accept, due to the clearances, that at the end of each stroke, thus at the reversal point, a short standstill of the drive spindle in the direction of movement will occur. This has a disadvantage effect on the even distribution of the color. Since the fork applies a certain amount of friction on the distributing roller, it may be that the distributing roller starts to slide in particular during starting, thus does not start correctly and the rated speed is reached anyhow only very slowly. The center removal of this movement from the main drive, in addition, makes it impossible to influence the distributing speed in any manner. This would be advantageous, however, in the case of some colors.
Also the drive for the doctor roller cannot directly be taken from the main drive, but it too must be converted, namely either into a continuous drive at a different peripheral speed or into a gradual drive with constant intervals. Here too exists the disadvantage that the rotational speed of the doctor roller cannot be adjusted to changing conditions, as for example the viscosity of the color, the desired operating speed, the prevailing temperature, etc.
Therefore, a purpose of the present invention is to produce a machine of the abovementioned type in which the important rollers, as for example the distributing roller and/or the doctor roller, can be controlled or influenced in a simple manner and continuously or steplessly in their movements, so that they can be adjusted to different conditions.
The invention provides that the axially movably supported, preferably hollow-cylindrical shell of the distributing roller is fixedly connected with respect to rotation to at least one axially directed curved surface, wherein a pin which is fixedly connected with respect to rotation to a spindle, which spindle is axially nonmovable and is arranged preferably coaxially with respect to the shell, rests on the curved surface, and wherein the shell and the spindle can be driven independently from one another.
Thus the distributing speed between the distributing roller and the respective abutting roller can be controlled and influenced in a simple manner such that the speed of the distributing shell and the drive spindle is different. The larger the speed difference, the higher is the axial distributing speed. However, if the speeds are the same, then the shell of the distributing roller does not carry out any back and forth movement. By controlling one of the rotational speeds, for example the one of the drive spindle, a very fine stepless or continuous control of the distributing speed can take place. Generally, the distributing shell is driven through other abutting rollers, while the spindle has a separate controllable drive. Since both parts of the distributing roller are driven, a safe starting is also assured and a slipping through or a slowing down due to the friction is impossible because the axial drive occurs substantially in an interlocked manner.